Control of SO/sub 2//NO/sub x/ emissions from low-rank coal combustion is investigated. This paper presents results from bench- and pilot-scal studies using pressure-hydrated lime and doped pressure-hydrated lime for the removal of SO/sub 2//NO/sub x/. These results indicate that greater utilization of sorbent may be achieved through pressure-hydration. Activation energies, reaction orders, and possible rate-limiting mechanisms for the sorbent-SO/sub 2/ reactions are also presented. The reaction of SO/sub 2/ with three sorbents formed by pressure hydration of quicklime was studied using thermogravimetric analysis and pilot-scale injection into a boiler. A semi-empirical pore-plugging model was used to describe the sulfation of dehydroxylated sorbents with good correlation of predicted and measured values of conversion. Activation energies of 26.8 to 49.0 KJ/mole were observed, the latter for a sorbent doped with sodium. Pilot-scale combustion were conducted firing natural gas. Injection temperature and baghouse temperature were nominally 1270/sup 0/K and 360/sup 0/ to 380/sup 0/K, respectively. Sorbent utilization values exceeding 70% at an alkali/SO/sub 2/ mole ratio of 1.0 have been observed. Simultaneous NO/sub x/ reduction of up to 20% has been observed. 14 references, 18 figures, 4 tables.